A planar light-emitting apparatus using an organic electroluminescent device is expected to have such applications as an ordinary illumination light source, a special illumination light source for art galleries and museums, and a backlight for an LCD, but has not yet reach full-fledged practical use. One of the major causes thereof is decrease in luminescence lifetime due to heat generation of the organic electroluminescent device itself.
Such an electroluminescent device is disclosed that has a pair of electrode on a substrate and a luminescent band provided between the electrodes, and also has a graphite sheet in contact with a surface of the substrate opposite to the pair of electrodes (for example, in JP-A-2003-59644), and in the device, heat formed on luminescence is radiated and uniformized by providing the graphite sheet.